The facet joints in the lumbar region of the spine are a source of lower back pain. These joints are located between each vertebra where they prevent excessive rotational motion of the spine. The facet joint is a protrusion of bone on each side of the vertebra that intersects with a protrusion on the vertebra above and below. The joint has a cartilage capsule that provides a lubricated surface for movement. If the facet joint becomes diseased, a patient often will experience pain.
An effective treatment for facet pain is fusion of the facet joint. The joint is fused by removing the cartilage in the joint and placing a spacer in the joint to immobilize the joint and allow the bone protrusions of the facet joint to grow together. A popular fusion technique utilizes insertion of a dowel in a hole drilled through the fact capsule to immobilize the joint and cause bone to grow across the joint and fuse the vertebras. The dowel may be natural bone or a synthetic material. This technique is usually effective, however in some instances the dowel migrates out of the drilled hole before the bones grow together and fuse. This problem occurs because the hole drilled between the two sides of the facet joint is smooth and there is no feature to retain the dowel. If the dowel migrates out of the drilled hole, the surgical procedure must be repeated. Thus, there is a need in the industry to address the aforementioned deficiencies and inadequacies.